1. Field of the Invention
The invention herein pertains to trailers for hauling wheel or track heavy equipment such as bulldozers, tractors or other vehicles and equipment. Particularly, the invention pertains to ramp mechanisms which are affixed to pivotable ramps at the rear of the trailer to facilitate loading and unloading of the heavy equipment.
2. Description of the Prior Art and Objectives of the Invention
various types of ramps have been used with trailers for many years to assist in loading and unloading heavy equipment such as bulldozers, tractors, trucks and other equipment which are transported from one site to another. Pairs of ramps allow the equipment to be driven onto the trailer with relative ease as such ramps are spaced to accommodate the wheel base width of the heavy equipment. Many types of ramps have been used through the years and include ramps which are pivotably attached and ramps which are disattached from the end of the trailer after use. In recent years pivotal ramps have been utilized which have springs of both the torsion and compression types. The springs are used to increase or supplement the manual forces necessary to raise the ramps once the loading or unloading process is complete. For example, single compression coil springs in the past have been placed on guide rods whereby, lowering the ramps which are attached at the rear of the trailer will compress the coil springs. After the equipment is driven up the ramp and onto the trailer, the operator can then raise and pivot the heavy ramps manually with the assistance of the compressed springs which add to the lifting forces. Such springs can provide one-half to two-thirds of the force needed to raise (pivot) the ramps thus making the operator's job much easier and greatly reducing the manual effort required. The raised ramps are then generally secured on the trailer in an upward posture until further needed.
Torsion springs have also been employed which are affixed to the axles of the ramps to apply a twisting force along the axles when the ramps are lowered. Thus, when raising a ramp the lifting force is supplemented with the torsion action of the spring which attempts to return to its relaxed configuration.
Due to the heavy weight of the ramps and the frequency of their use, it is not uncommon for the single coil springs for each ramp to lose their memory and become weakened over a relatively short period of time. Also, there has not been available a suitable ramp mechanism which will allow lateral adjustments of the ramps to accommodate various equipment wheel base widths of different heavy equipment in a convenient manner.
Therefore, with the problems and disadvantages associated with conventional spring loaded trailer ramps, the present invention was conceived and one of its objectives is to provide a ramp mechanism whereby the ramps can be easily laterally adjusted for various wheel or track base widths of heavy equipment vehicles.
It is another objectives of the present invention to provide a ramp mechanism which includes a means to adjust the tension of the coil springs employed.
It is yet another objective of the present invention to provide a coil spring assembly which includes a pair of coil springs on each guide rod for additional resilient force.
Various other objectives and advantages of the present invention will become apparent to those skilled in the art as a more detailed description of the invention is presented below.